<!DOCTYPE HTML>
<html>
<body>
<iframe src="data:text/xml,
<html xmlns='http://www.w3.org/1999/xhtml'
onDOMAttrModified='window.frameElement.parentNode.removeChild(window.frameElement)'>
</html>"
onload="event.target.contentDocument.documentElement.setAttribute('x', 'y');"></iframe>
</body>
</html>